#include <iostream>
#include <math.h>
using namespace std;

int main() {
    unsigned int a,b,c;
    bool res = false;
    cin >> a >> b >> c;
    
    if (a + b > c && a + c > b && b + c > a)
    {
        res = true;
    }

    if (res) {
        cout << "yes";
    } else {
        cout << "no";
    }
    
    return 0;
}